Timestamp Interfaces

Two interfaces provide timestamps. gettimeofday(3C) provides the current time
in a timeval structure, representing the time in seconds
and microseconds since midnight, Greenwich Mean Time, on January 1, 1970. clock_gettime, with a clockid of CLOCK_REALTIME, provides the current time in a timespec structure, representing
in seconds and nanoseconds the same time interval returned by gettimeofday(3C).

SunOS uses a hardware periodic timer. For some workstations, the
hardware periodic timer is the sole source of timing information. If the hardware
periodic timer is the sole source of timing information, the accuracy of timestamps
is limited to the timer's resolution. For other platforms, a timer register
with a resolution of one microsecond means that timestamps are accurate to
one microsecond.